Calendar Effect

The theory that certain days of the week, weeks of the month, and months of the year are more likely to produce rises/falls in share prices than others. 'Sell in May and go away' is an example. One stock market commentator has claimed that the 6th June is the best trading day of the year, that 26th September is the worst, prices more often than not fall during the last week of October, and that the UK stock market usually rises in January in US presidential election years.